Mollusc feeding guilds on sandy beaches in São Paulo State, Brazil

The feeding guilds of four communities of molluscs living in the intertidal zone of Enseada in Caraguatatuba Bay and Barra Velha and Araçá beaches along the São Sebastião Channel were identified. Three-letter codes were assigned to each feeding guild, identifying the feeding habit, mobility patterns related to feeding, and food-capturing structures. Data were obtained from qualitative analyses of the digestive tract contents and from observations on the feeding behaviour of the gastropod Olivella minuta and the bivalves Tagelus plebeius, Macoma constricta, Tellina lineata, and T. versicolor. These data were complemented by published information on the feeding of congeneric or confamilial species. Six feeding guilds were identified. The SDS (suspension-feeder, discreetly motile, inhalant siphon and ctenidia) and DDS (deposit-feeder, discreetly motile, inhalant siphon and ctenidia) groups were more abundant. Suspension-feeding bivalves showed higher Trophic Importance Index (TI) values in all the study areas. Deposit-feeders showed high TI values only at Barra Velha beach. The species in the SDS feeding guild tended to occur in areas with lower salinity and moderately to well-sorted sediments with very fine sand predominating. The distribution of the feeding guilds correlated best with salinity, particle size distribution, and the contents of silt-clay and organic matter in the sediment.